1. Field of the Invention
The present invention relates to a molding material having high dynamic strength which entails ribbon-like microfibrils of bacterial cellulose.
2. Description of the Background
Bacterial cellulose has been used in the production of medical pads. In particular, such pads utilize the sheet-like cellulose produced by Acetobacter xylinum ATCC 23769. See Japanese Published Examined patent application No. 120159/84.
On the other hand, various materials are known as conventional molding materials. For example, it is known that cellulose, cellophane, and celluloid, obtained by dissolving cellulose derivatives and then finishing the same, are known, as well as fibers for thread-like, sheet-like or various solid moldings. Various synthetic high molecular weight materials have also been developed and include those having improved dynamic strength by the orientation of molecular chains in a definite direction.
The dynamic strength of conventional cellulose and cellulose derivatives derived from various plants is not very great. For example, the modulus of elasticity of celluloid or cellophane in sheet form is approximately 2 to 3 GPa at the maximum.
Moreover, synthetic high molecular weight materials obtained by orienting the molecular chains in a definite direction have been found to have limited utility due to the poor modulus of elasticity in the other directions. For this reason, materials having no anisotropy in molecular orientation but having excellent strength as structural materials have been desired. However, high molecular weight materials in which molecules are arranged at random exhibit a poor modulus of elasticity. As molding materials of synthetic high molecular weight having high efficiency, polyester films, aramid sheets, polyimide films and the like are known, but the module of elasticity of the same are approximately 4 to 7 GPa.
Thus, at present, bacterial cellulose has been used only in the preparation of medical pads. Such material has never been used, nor is anything known about the use of the same, in the preparation of items having high dynamic strength.
Nevertheless, a need clearly continues to exist for a molding material which has both excellent elasticity and high tensile or dynamic strength.